Communication between cells of the immune system is integral to immune function. The process of T cell differentiation and maturation involves direct contact between dendritic cells and the maturing T cells, during which the T cells are selected for survival on the basis of their ability to recognize antigens associated with “self” without triggering an immune response, thereby preventing auto-immunity. Once mature, T cells frequently interact physically with antigen presenting cells, which expose the T cell to non-self antigens from bacteria, viruses, etc., ultimately triggering expansion of T cell populations that elicits a sustained immune response against the antigen source presented.
The study of inter-cellular communication is greatly facilitated by imagery of the cells in contact. Ideally, the imagery would be acquired from living cells; since it is likely that fixation of the cells would disrupt biochemical signaling mechanisms. Since the cells would be alive and therefore highly dynamic, it would be desirable to acquire multiple images of conjugated cells simultaneously. It would also be desirable to image the cells directly in fluid suspension, since immune cells are generally non-adherent and contact with a foreign surface could perturb the signaling process. Finally, it would be desirable to provide a sufficiently analytical throughput such that studies could employ the relatively rare primary T cell and antigen presenting cell conjugates obtained from whole blood, as opposed to model systems of cultured cells, to best model in vivo behavior.
Thus, there is a recognized need in the art for techniques that permit detection and quantization of cell conjugates in flow, which would provide an opportunity to study suspension-based cell lines and primary cells. Furthermore, methods for preparing cells in suspension for multi-spectral analysis are needed. The present invention meets such needs, and further provides other related advantages.